1. Field of the Invention
Aspects of the present invention relate to an optional tray fastening device for an image forming apparatus, the optional tray, and an image forming apparatus.
2. Description of the Related Art
Generally, image forming apparatuses, which are sometimes referred to by the term “office machines” include multifunction apparatuses, photocopiers, facsimile machines, and printers. Image forming apparatuses generally comprise a main body and may have an optional tray additionally connected to a lower part of the main body.
For example, in an image forming apparatus, the main body comprises a developing unit, a fixing unit, and a laser scanning unit. In addition, a print medium supply tray for supplying a print medium such as paper to the developing unit is mounted at a lower part of the main body.
The print medium supply tray may be joined to the main body or may be separably mounted to the main body as an optional part. Recently, print medium supply trays have been configured so that a plurality of print medium trays can be layered, to supply various types of print media.
Therefore, such print medium trays usually have a layerable structure so that two or three print medium trays can be layered according to the user's demand and are separably mounted with respect to the lower part of the main body. Herein, such print medium trays are referred to as “optional print medium supply trays” or, for short, “optional trays.”
More specifically, a hole is formed at the lower part of the main body or the print medium supply tray while a shaft is formed at an upper part of an optional print medium supply tray. The shaft is configured to be inserted in the hole formed at the main body. By fitting the shaft into the hole, the optional print medium supply tray can be attached to the main body or to the lower part of the print medium supply tray.
However, the above connection method using the hole and the shaft has the following problem.
Such a simple connection using a hole and the shaft prevents the optional print medium supply tray and the main body from moving laterally with respect to each other, but does not prevent the shaft from leaving the hole. Therefore, the connection can be easily released when carrying or tilting the main body with the optional print medium supply tray attached thereto. As more and more optional print medium supply trays are added, this danger increases.